Speed limits of 20mph could be introduced across 90% of the roads in Birmingham, under a proposal being considered by the city council.
Major roads would keep existing 30mph and 40mph limits, except near "local [shopping] centres, schools and hospitals", the council said.
The authority estimates introducing the new limits will cost £7m.
Councillor Victoria Quinn said: "This is how we can reduce casualties and road deaths - it's the simplest way."
Other cities, including Manchester and Bristol, have already adopted city-wide 20mph limits, according to the council.
If the plan is approved the lower limits will be rolled out across the city over seven years, Ms Quinn said.
It would include major roads that run through areas with a high number of shops, such as the Alcester Road and King's Heath High Street.
The cost of the scheme would come from the local transport plan, according to the local authority.
It has also successfully bid for £800,000 from the Cycle City Ambition Fund bid, which supports the introduction of 20 mph limits.
The council believes the lower limit could save approximately £5m per year based on a "conservative estimate" of the reduction of the number of collisions at 78 per year.
Ms Quinn believes the lower speed limits will also reduce the number of fatalities on the city's roads.
"There are headlines with this that you cannot argue with. If you hit someone at 20mph instead of 30mph there is less damage and that saves lives," she said.
Sarah Birch, 35, from Stourbridge, said: "I think it's a good idea because it's quite a populated area."
John Jordan, a 68-year-old retired man from Wolverhampton, said a lower speed limit would keep traffic moving and reduce "cutting up or blocking up".
John Lewis, a 43-year-old plumber from Hagley, said: "I can't imagine it will make much difference. We have to go slow enough as it is."
The council said the new speed limits would mainly be enforced with "traffic signs and road markings".
At some locations further measures such as "gateway treatments, additional physical traffic calming measures and variable speed limits" may be required, it said.
The policy will go to the council for approval in the New Year after a public consultation running from 21 October until the end of November.